Managing Green Roofs Against Pest Pressures

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Contributed by Orkin, LLC

From energy efficiency to water conservation, office and commercial building personnel are often tasked with taking responsibility for environmental contribution. Property managers must consider the impact their current decisions are having on the environment — and how to start implementing solutions that will secure a better future. One common way this is done is by installing a green roof on the structure.

Despite the benefits, there’s a reason for caution: the greenery on your roof could be putting you at risk for a pest introduction. The rooftop soil and vegetation create an attractive sanctuary for pests, offering easy sources of food, shelter and water.

So, when it comes to pests, “going green” includes proactive, preventive measures that eliminate or reduce the conditions attractive to pests. This approach, known as Integrated Pest Management (IPM), is crucial to ensuring your facility stays on the road to preventing pest activity on an ongoing basis while being environmentally responsible.

Common Green Roof PestsTo help combat the threat of increased pest activity on your property, it’s important to know what types of pests to look for, and the proactive steps you can take to keep them away.

• Plant-feeding insects and ants – Plant-feeding insects such as aphids can be found on plant stems and leaves where they feed on liquid juices within the plant. They produce a “honeydew sap” that draws in other pests, especially ants.

• Mosquitoes – Especially in the warmer months, mosquitoes take refuge and lay eggs in standing, stagnant water sources, which can be found on rooftops especially those with many potted plants or other roofscapes). Ponds, fountains and other artificial water features create ideal environments for mosquito breeding.

• Stinging and nesting pests – Stinging insect pests such as bees, hornets, wasps and yellow jackets are attracted to flowers and water fixtures. They can build nests inside gutters, within trees or in bushes, in the soil of landscape or potted plants, and on the corner or exterior wall voids of buildings. Additionally, birds use your landscaping as a nesting site, enticed by the shelter and abundance of food and water provided. Birds can build nests around plants and in other protected areas.

• Rodents – Rodents, especially rats, also take refuge on green roofs, burrowing through vegetation and mulch as they feed on the seeds, fruit, or bulbs of ornamental plants.

When protecting your building, it’s important to implement an environmentally responsible approach. A few proactive measures you can take include: implementing maintenance routines and other prevention tactics, building a strong partnership with your pest management provider and educating your staff on basic IPM knowledge, roles and protocol.

Maintenance Routines And Prevention TacticsThe roof can be commonly forgotten in your crew’s maintenance routines (both with or without a green roof). Including it in your maintenance schedule is key to help preventing and reducing pests on your green roof. As you develop an Integrated Pest Management plan, proactive inspection, sanitation and maintenance should be three main components of your strategy.

Exclusion tactics also help prevent pests from getting into your building in the first place. Here are a few things that you can do to keep pests off your green roof and out of your building.

• Avoid plants that produce nuts, fruit and seeds, as these plants attract pests looking for food. Talk to your pest management or landscape provider about other species of vegetation you should avoid, helping lessen pest activity.• Use cedar mulch instead of organic mulch. Cedar mulch keeps away certain types of ants, such as the Argentine ant. Also, reduce the use of mulch in planters, and ivy overgrowth, to minimize the availability of food and shelter for pests. • Ensure your pest management provider or landscape specialist has a plan for resolving plant-feeding insects, as the sap they produce attracts other pests.• Minimize the build-up of water from leaky taps, air conditioning units and irrigation by correcting drainage blockages and repairing leaks and other excess moisture sources. • Repair or replace torn and missing vent screens. • Seal cracks, holes and other potential entry points in exterior masonry.

Working With A Pest Management ProviderYour relationship with your pest management provider should surpass typical vendor status. Your pest management provider should be a partner who takes the time to design an IPM program specifically for your property, adjusting the plan over time as pest pressure and your pest management needs evolve. Keep your pest management professional updated when something changes that may alter the effectiveness of your IPM program, such as a change in your property’s waste disposal schedule.

An effective IPM plan also requires a higher standard of scientific expertise, including knowledge of pest biology, pest behavior and the latest green technology in the industry. So, it’s important that your provider is proficient in these areas.

Train Staff On Roles And ProtocolBecause pest pressures can be detrimental to your business’s reputation, it’s crucial to include your employees in pest management efforts to strengthen your defense. More eyes looking out for pests — and more individuals aware of the potential outcomes of unknowingly bringing pests into the facility — will increase the likelihood of spotting a problem before an infestation gains ground in your building. Your whole team needs to know what to look for and how to report any potential pest activity or conducive conditions.

• Work with your pest management provider to provide IPM trainings for your employees to help them gain an understanding of your pest control protocols, and the role they play in preventing and controlling pest activity. • Consider assigning each staff member to a specific pest management role based on their daily responsibilities. For example, a person who handles sanitation should monitor for and clean any liquid or product spills that could attract pests.

As sustainable construction progresses, understanding the implications of vegetative roof systems is the cornerstone of maintaining their effectiveness and utility. While green roofs can increase pest pressures at your property, the right maintenance strategy should alleviate concerns and help you create an environment that everyone can enjoy. If you incorporate pest management into your planning, you can stay ahead of the curve to ensure your green roof thrives.

Tim Husen is Technical Services Manager for Orkin. A board-certified entomologist specializing in urban entomology, he has more than a decade of experience in the industry.

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